The increasing integration of LSIs has led to finer and finer circuit line widths of semiconductor devices. An approach employed to form desired circuit patterns on semiconductor devices uses a step-and-repeat exposure system to reduce and transfer, onto a wafer, a high-precision master pattern (also called a mask, or a reticle particularly when used in a stepper or scanner) formed on a piece of quartz. The high-precision original pattern is written with an electron beam writing apparatus by use of a so-called electron beam lithography technique.
When electron beam drawing is performed, first, the layout of a semiconductor integrated circuit is designed, and layout data (design data) is generated. The layout data is converted to drawing data, and is inputted to an electron beam drawing apparatus. The electron beam drawing apparatus performs drawing based on the drawing data.
Meanwhile, in order to improve a throughput, development of drawing apparatuses using multi-beam has been pursued. A large amount of beam can be irradiated at once (one shot) using a multibeam, as compared with the case where drawing is performed by a single electron beam, and thus the throughput can be significantly improved. In a multi-beam type drawing apparatus, for instance, electron beams discharged from an electron gun are passed through an aperture member having multiple holes, and a multi-beam is formed, blanking control is performed by a blanking plate on the beams, beams which are not shielded are reduced by an optical system, and are emitted to a substrate mounted on a movable stage.
For instance, in drawing using such a multi-beam or raster drawing with a single beam, drawing data (pixel data) using gray beam is generated for each pixel.
However, radiation amount data needs to be generated for each pixel of size 10 nm, for instance, thus data volume is increased, and data transfer cannot be performed efficiently.